10kHz Pulse Repetition Frequency CO2 Laser for Processing High Damage Threshold Materials

Power intensities generated at the workpiece by continuous wave carbon dioxide lasers at 10.6 mum are insufficient to induce the non-conduction limited processes necessary for machining many of the refractory metals and ceramics employed in the manufacture of engineering components. Operated in a pulsed mode, analogous to solid state laser operation, the CO2:N2 laser can be designed to overcome these power intensity limitations. Nitrogen Carbon-dioxide mixtures can be pulse excited to give high output pulse intensities combined with a relatively low mean output power, thus, minimising thermal degradation of the optical system. Flat topped pulses with plateau powers controlled and matched to the processing requirements of metals and ceramics can be generated by proper choice of the input electrical pumping pulse, gas composition and design parameters of the optical resonator. Continuous machining is possible provided pulse repetition frequencies of up to 10 kHz can be achieved, since, at this frequency, a constantly evaporating liquid phase can be sustained